Google Benchmark

Google Benchmark

Google Benchmark is a C++ library specifically designed for microbenchmarking – measuring the performance of small code snippets with high accuracy. Microbenchmarking is essential for identifying bottlenecks and optimizing critical sections, especially in performance-sensitive applications.

Google Benchmark simplifies this process by providing a framework that manages iterations, times execution, and performs statistical analysis. This allows you to focus on the code being measured, rather than writing boilerplate or trying to prevent unwanted compiler optimizations manually.

To use Google Benchmark, define a function that accepts a benchmark::State& parameter and iterate over it to perform the benchmarking. Register the function using the BENCHMARK macro and include BENCHMARK_MAIN() to generate the benchmark’s entry point.

Here’s a basic example:

    

        
        
#include <benchmark/benchmark.h>

static void BM_StringCreation(benchmark::State& state) {
  for (auto _ : state)
    std::string empty_string;
}
BENCHMARK(BM_StringCreation);

BENCHMARK_MAIN();

    

Filtering and Preventing Compiler Optimizations

Google Benchmark provides tools to ensure accurate measurements by preventing unintended compiler optimizations and allowing flexible benchmark selection.

1. Preventing Optimizations: Use benchmark::DoNotOptimize(value); to force the compiler to read and store a variable or expression, ensuring it is not optimized away.

2. Filtering Benchmarks: To run a specific subset of benchmarks, use the --benchmark_filter command-line option with a regular expression. For example:

       
   
           
           
   ./benchmark_binary --benchmark_filter=BM_String.*
   
       
   

This eliminates the need to repeatedly comment out lines of source code.

For more detailed information and advanced usage, refer to the official documentation .